Datum planes are used as a reference on a part where a reference does not already exist. For example, you can sketch or place features on a datum plane when there is no other appropriate planar surface. You can also use a datum plane as a reference to place set datum tag annotations.

How do you define datum?

A datum is a plane, a straight line, or a point that is used as a reference when processing a material or measuring the dimensions of a target. ISO Definition. Types of Datums.

What is datum plane in geography?

A permanently established horizontal plane, surface, or level to which soundings, ground elevations, water-surface elevations, and tidal data are referred; e.g., mean sea level is a common datum plane used in topographic mapping.

Where do you put datums?

We can place the datum symbol either on the surface or on one extension line from the surface. For any surface other than a round cylinder, the datum is strictly on the side where the symbol is shown. However, for a round cylinder, the datum is the entire round surface.

What is the electrical datum plane?

1) In land areas subject to tidal fluctuation, the electrical datum plane is a horizontal plane 2-feet above the highest tide level for the area occurring under normal circumstances, that is, highest high tide.

What is datum plane in GD&T?

A datum is theoretical exact plane, axis or point location that GD&T or dimensional tolerances are referenced to. … All GD&T symbols except for the form tolerances (straightness, flatness, circularity and cylindricity) can use datums to help specify what geometrical control is needed on the part.

What is a datum surface?

In engineering and drafting, a datum is a reference point, surface, or axis on an object against which measurements are made.

What is data and datum?

Data (US: /dt/; UK: /det/) are individual facts, statistics, or items of information, often numeric. In a more technical sense, data are a set of values of qualitative or quantitative variables about one or more persons or objects, while a datum (singular of data) is a single value of a single variable.

What is a datum and how is it used?

A geodetic datum is an abstract coordinate system with a reference surface (such as sea level) that serves to provide known locations to begin surveys and create maps. In this way, datums act similar to starting points when you give someone directions.

What is datum on a map?

A datum is a model of the earth that is used in mapping. The datum consists of a series of numbers that define the shape and size of the ellipsoid and it’s orientation in space. A datum is chosen to give the best possible fit to the true shape of the Earth. … Another example, familiar to GPS users, is the WGS-84 datum.

What is the most commonly used datum plane?

The North American Datum of 1983 (NAD 83) is the most current datum being used in North America. It provides latitude and longitude and some height information using the reference ellipsoid GRS80.

What is a datum line for?

Datum-line meaning (engineering) A line which serves as a reference or base for the measurement of other quantities.

What is a simulated datum?

A simulated datum is a point, axis or plane established from the actual surface of the datum feature simulator. … Simulated datum: A point, axis, or plane established by processing or inspection equipment, such as the following simulators: a surface plate, a gage surface, or a mandrel.

What is a datum in statistics?

Statistical data. Datum. An item of factual information derived from measurement or research (singular of data)

What are datum targets?

A datum target is a point, line, or limited zone on a target with which machines and instruments for processing, measuring, and inspection come into contact in order to establish a datum.

What is a datum plane quizlet?

What is a datum? theoretical exact plane, axis or point location that dimensional tolerances are referenced to. … a plane or axis, or point. they are measuring aspects of the actual geometry to assess how closely they match with the nominal value.

How do you identify a datum?

The datum features on a drawing are denoted with a series of capital letters. These letters are in boxes and tied to the datum feature with a black triangle. This letter will also show up in any feature control frame that uses this datum feature as a reference.

Which datum is used by Google Earth?

Google Maps and Microsoft Virtual Earth use a Mercator projection based on the World Geodetic System (WGS) 1984 geographic coordinate system (datum). This Mercator projection supports spheres only, unlike the ESRI Mercator implementation, which supports spheres and ellipsoids.

What is primary datum?

The primary datum feature has at least 3 points of contact with its datum plane. The secondary datum feature has at least 2 points of contact with its datum plane. The tertiary datum feature has at least one point of contact with its datum plane. The 3-2-1 Rule and Points of Contact.